There has been recently an increasing demand for an NC lathe provided with a turret device since a machining apparatus, particularly, a lathe is able to realize automatic machining operations at high speed and can cope with a computer-integrated flexible manufacturing system.
The turret device is structured such that a rotary table called a turret which is provided on a tab base table (tool slide), and has normally 5 to 12 indexing positions, is indexed while rotated (hereinafter referred to as simply indexed). Tool mounting portions are formed on an outer periphery or end surface of the turret, and various tools such as turning tools and drills are mounted on these tool mounting portions wherein an appropriate tool is selected from the various tools depending on the type of machining process desired so as to index the selected tools in machining positions. Such an indexing of the turret is performed by the driving force from an indexing actuator.
The turning tools and drills can be frequently mounted on the tool mounting portions of the turret, wherein machining such as drilling a hole into a workpiece can be performed by driving the turning tools mounted on the tool mounting portions.
Since the indexing, positioning and fixing of the turret in the conventional turret device have been performed by a hydraulic cylinder as a driving source, a large-sized power unit comprising a hydraulic pump, an electric motor for driving the pump, an oil tank, etc. has been needed.
An arrangement using an electric motor for indexing a turret has been known wherein the positioning and fixing of the turret has been performed by the hydraulic cylinder, which is indispensable to the power unit.
Even if the indexing of the turret is performed by the electric motor, the motor for driving the turning tool is provided in addition to the motor for indexing the turret, whereby the turning tool is driven and turned by a driving force of the motor for driving the turning tool, thereby performing the machining of the workpiece.
However, since it is not necessary that the indexing of the turret and the driving of the turning tool be performed at the same time, it is possible to reduce the cost of the parts and to perform an easy control if the indexing of the turret and the driving of the turning tool can be achieved by a common electric motor.
Further, if the driving source for positioning and fixing the turret comprises the electric motor, the reduction of components and the easy control are further enhanced.
Since the present invention has been made in view of the above concept, it provides a turret device capable of achieving the indexing of the turret and the driving of the turning tool by a common electric actuator, thereby eliminating the power unit.